The co-rotating twin-screw extruders have been widely applied in the fields such as filling, modifying, blending, and reactive extruding polymeric materials, etc. The principle is that: the structures of the two screws are identical, when assembled, there is a certain phase angle between them, the centerline distance is related to the number of screw tips and the peak angle, and the rotation speeds of the two screws are the same during the processing process. To achieve the self-cleaning effect during the processing process, from the viewpoint of relative movement, the two screws keep constant in the phase therebetween, contact and make a translational movement each other. Although this structure can preliminarily solve the problems such as the poor mixing property, the poor self-cleaning property, and the poor venting effect, etc., during the material processing process, there are still the following defects: (1) as the shapes of the two screws are the same, there are consistency (symmetry) therebetween, so that there is a consistency in the geometrical space through which the fluids pass during they proceeding along the two screws, there is an absence in the conversion between the geometric shapes of the spaces for processing the fluids, the reorientation effect of the interface during the shearing process is attenuated, and the mixing effect is limited, especially, that most of the fluid mixing in the core region of the screw channels is still laminar mixing, and the interface is increased linearly with time; and (2) the studies have shown that the co-rotating twin screws can only make an effective mixing effect on the surface layer fluid near the wall region, especially in the engaging region, the effect is extraordinarily obvious, in general, and there is still an extremely large possibility for improvement in the fluid mixing in the core regions.
For this, as required, there is a need for providing an extruding process with a self-cleaning effect, and a well-mixing effect.